Condition control device and system

ABSTRACT

Protection against refrigeration compressor burnout by short cycling is provided by a timer having an electric motor. This motor is initially energized through a circuit in series with a thermostat and the contactor coil. The motor is then transferred to a circuit shunting the thermostat and then the timer load switch closes energizing the contactor. This shunts the timer motor and stops it. When the thermostat is satisfied, it drops out the contactor and breaks the shunt circuit for the timer motor allowing it to run back to the starting point where the motor is again placed in series with the thermostat. A variable delay is provided by a second timer motor switch which first energizes the motor in parallel with the contactor coil.

United States Patent [72] Inventor John L. Harris 2,730,336 1/l956Shiers 62/157(X) l N gellfield, 3,300,990 1/1967 Jaremus 62/158(X) [2 1]p sooll Primary Examiner-Robert S. Macon [22] Flled Aug. 14, 1969 A E[45] Patented Apr. 6, 1971 ssistant xammer- 1 ram J. Smith [73] AssigneeDeltrol Corp. Bellwood, Ill.

ABSTRACT: Protection against refrigeration compressor bur- 54 CONDITIONCONTROL DEVICE AND SYSTEM nout by short cycling is provided by a timerhaving an electric 14 Chins, 4 Drawing FigS motor. This motor isinitially energized through a circuit in se- C ries with a thermostatand the contactor coil. The motor is [52] I 307/116, then transferred toa circuit shunting the thermostat and then 62/158 62/231 the timer loadswitch closes energizing the contactor. This hat. Cl-

h t th tim motor and tops when the thennostat is Field ti fi d it d o tthe co tactor and breaks the shunt ir- 231; 307/1 16, 1 17 'cuit for thetimer motor allowing it to run back to the starting point where themotor is again placed in series with the ther- [56] References Citedmostat. A variable delay is provided by a second timer motor UNITEDSTATES PATENTS switch which first energizes the motor in parallel withthe con- 2,152,250 3/1939 Gay 62/157(X) tactor coil.

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O 2osEc.

I5 40 sec.

INVENTOR.

CONDITION CONTROL DEVICE AND SYSTEM This invention relates in general toautomatic controls and more particularly to time and temperature controlsystems for refrigeration compressors.

The primary object of the invention is to provide a simple controlsystem for stopping and starting a compressor and blower motor of arefrigeration system at the command of a condition responsive device andto provide a delay between compressor energizations to protect thecompressor against short cycling.

A further object of the invention is to provide a system providing apressure equalization delay after the compressor stops and before it canbe restarted, this delay being timed even though the conditionresponsive device is not calling for cooling.

Another object of the invention is the provision of a compressor controlsystem which on a normal cycle interposes a pressure equalization delayperiod before restart of the compressor and which interposes a longerdelay in event of a system malfunction.

A further object is the provision of a simple control system in which atiming mechanism performs all of the control functions and eliminatessolenoids, relays, etc., required in prior art devices.

Other objects will appear from the following description and appendedclaims.

For a full disclosure of the invention, reference is made to thefollowing detailed description and to the accompanying drawings inwhich:

FIG. 1 is a schematic illustration of a refrigerator compressor controlsystem in which the timing means provides a variable delay betweencompressor restarts depending on the duration of the last cycle;

FIG. 2 is a switch operation chart of the embodiment of the inventionshown in FIG. 1;

FIG. 3 is a schematic illustration of the system providing a fixedminimum timed interval between stopping and restarting of the compressorand also providing blower control;

FIG. 4 shows a modification of the general arrangement shown in FIG. 3,but which provides an additional delay in restart if the stoppage isfrom the limit control, the additional delay period depending upon howlong the limit control switch is open;

FIG. 5 is a sequence chart applicable to both FIGS. 3 and 4;

FIG. 6 shows schematically a system providing a minimum delay between anormal stop and restart of the compressor sufficient to provide pressureequalization, and in which the delay is increased a variable amount ifthe compressor stops on a short cycle;

FIG. 7 is a switch operating chart illustrating the operation of FIG. 6.

FIGS. 1 AND 2 Referring to FIG. 1, reference character 1 indicates atimer motor driving cams 2 and 3 in a clockwise direction. The cam 2actuates a cam follower 4 which in turn actuated a switch blade 5carrying a contact 6. A second switch blade 7 carries a contact 8cooperating with contact 6 on blade 5. Blade 7 also carries a contact 9cooperating with a stationary contact 10.

The cam 3 actuates a snap switch 11, having a normally closed contactT-2 and a normally open contact T-3.

The control system also includes a contactor coil 13 having a holdingcontact 01 and load contacts C-2 and C-3, con trolling the compressormotor 14. The control system also includes an operating control orthermostat 15 and a safety control or high-low pressure cutout 16.

With the parts in the position shown, the system is in the standbyposition in which the compressor is off and the system is ready to starta new cycle. When the thermostat 15 calls for cooling, it establishes astarting circuit for the timer motor 1 as follows: line wire 17,switches 15 and 16, leads 19, timer motor 1, switch T-2, and contactorcoil 13 to line wire 18. The impedance of the timer motor 1 is manytimes greater than the impedance of the contactor coil 13 and thus thetimer motor at this time runs substantially at full voltage and thecurrent draw is insufficient to affect the contactor. A short time afterthe timer motor 1 starts (as shown in FIG. 2), the cam 3 causes switch11 to open contact T-2 and close contact T-3. This establishes a circuitfor the timer motor 1 independent of contactor coil 13 and direct to theline wire 18. At a predetermined time after starting of the motor 1,such as 2 minutes, the switch T-1 closes momentarily. In this action,the cam follower 4 raises switch blade 5 which engages contact 8. Thiscompletes a series circuit through the normally closed con tacts 9 and10 around the contactor holding switch C-l thus energizing the contactorcoil. Contacts C-l, C-2 and C-3 now close. Contact C-l completes aholding circuit around the timer switch T-l. Contacts C-2 and C-3energize the compressor motor 14. In a few seconds after contacts 5 and8 engage, contacts 9 and 10 open, thus opening the timer starting switchT-l. The compressor is now in operation and the timer motor 1 continuesto run through contacts T-3 which are now closed. A period of time afterswitch T-l closed, the cam follower drops down an abrupt dropoff on thecam 2. This allows contacts 9 and 10 to reengage. However, during thedownward motion of blade 5, this blade 5 moves faster than blade 7 andthus contacts 6 and 8 are open when contacts 9 and I0 reengage. Thus theswitch T-l closes only momentarily at one point in the revolution of cam2. Should the contactor coil 13 be deenergized at any point in thecycle, the holding contact C-l opens instantly and the timing mechanismmust return to the position in which switch T-l momentarily closesbefore the compressor can be restarted.

Assuming a normal cycle, the timer will continue operation to completeits revolution from the starting point which may take for example 5minutes. At this time, the timer cam 3 operates switch 11 to opencontacts T-3 and reclose contacts T-2. Closure of the switch T-2connects the timer motor 1 back in series with the contactor coil 13.However, at this time the timer motor is now shunted by the contactorholding switch C-] which is closed. The timer motor 1 is thereforedeenergized and stops at this point. When the thermostat 15 becomessatisfied it breaks the circuit to the contactor coil 13 openingcontacts 01, C-2 and C-3. The compressor motor stops and the shuntcircuit around the timer motor 1 is broken. Thus when the thermostatagain calls for cooling, a starting circuit for the timer motor 1 isagain provided in series with the contactor coil 13.

From the foregoing, it will be apparent that the embodiment of theinvention shown in FIG. 1 provides a variable delay cycle. Following anormal cycle, the delay in starting the compressor after the thermostatcalls for cooling will be only 2 minutes. However, if the system shouldshort cycle, for example 15 seconds after starting, the delay would bethe balance of the timer cycle, namely 4 minutes 45 seconds. Thisvariable delay is caused by operation of the timer motor for a period oftime after the compressor is started by the timer.

FIG. 3

In this embodiment of the invention, the timer motor stops when thecompressor is energized and then runs back to the starting positionduring the normal off period of the compressor.

Timer motor la drives cams 2a, 3a and 20 in a clockwise direction. Cam2a operates a momentary switch T-1 which is of the same constructionshown in FIG. 1. Cam 3a operates a snap switch 22 having normally closedcontacts T-4 and normally open contacts T-S. Cam 20 operates a snapswitch T-6 having normally open contacts controlling the blower motor21. This blower motor may drive a blower for the evaporator or condenserof the refrigeration system, or both. The timer motor la in thisembodiment of the invention has one side connected directly to thecontactor coil 13a by lead 21. The other side of the timer motor isconnected to the common terminal of snap switch 22 and is thuscontrolled by contacts T4 and Tc5.

In this embodiment of the invention, no holding switch for the contactoris required. The contactor includes only contacts C-2 and C-3controlling the compressor motor 14a.

In operation, assuming the limit control switch 16a is closed and thethermostat 15a calls for cooling, a circuit is established to the timermotor from the line wire 17a, limit control 160, thermostat 15a, lead25, switch T4, lead 24, timer motor la, lead 23 and contactor coil 13ato wire 18a. This timer motor la thus starts revolving cams 2a, 3a and20 in a clockwise direction. As shown in the chart FIG. 5, the switchT-4 opens and switch T-S closes in approximately l seconds. Thisestablishes a new circuit to the timer motor from line 170 through lead26, this circuit shunting out the limit control switch 160 and thethermostat switch 15a. In approximately 15 seconds from start, timerswitch T-6 closes which places blower motor 21 in operation.Approximately 20 seconds from start, the switch T-l closes whichenergizes the contactor coil assuming that the thermostat switch 15a andlimit control switch 160 are still closed at this time. The contactorcoil 13a on being energized, closes compressor contacts C-2 and C-3starting the compressor motor. Closure of momentary switch T-1 alsoestablishes a shunt circuit for the timer motor through limit control160, thermostat 15a and timer switch T-l. This causes the timer motor tostop with the switch T-l closed.

The system will operate with the timer motor off, the compressor motoron and the blower motor on until either the thermostat 15a becomessatisfied or the limit control switch 16a indicates an unfavorablecondition in the system. If either occurs, the shunt circuit for thetimer motor 1a is broken and the contactor coil 13a is deenergizedstopping the compressor motor 14a. The timer motor In begins running andin a second or two reopens the switch T-l. Reopening of switch T-lmaintains the shunt circuit for the timer motor open and also preventsreenergization of the contactor coil 130 until the timing mechanism hascompleted a full cycle and returns to the point where switch T-] isreclosed.

A predetermined time after the timer motor resumes operation, switch T-6opens which stops the blower motor. The timer motor will continue to beenergized in circuit with switch T and the contactor coil until the endof the 5-minute cycle at which time switch T-S opens and switch T-4recloses. This stops the timer motor until switches 15a and 16a are bothclosed for starting a new cooling cycle.

From the foregoing it will be apparent that in this embodiment of theinvention, the thermostat on call for cooling places the timer motor inoperation in series with the contactor coil. First a maintaining circuitis established for the timer motor through switch T-5. Then momentaryswitch T-l closes which starts the compressor and shunts the timer motorthus stopping the motor. This shunt circuit is broken by opening ofeither the thermostat or limit control switch which stops the compressorand simultaneously starts the timer motor. This will run the timingmechanism back to the standby position during the off period of thecompressor. In addition, this embodiment of the invention provides forhaving the blower motor on before the compressor is started andmaintaining it on for a short period after the compressor is stopped. Inthis embodiment of the invention the delay imposed between stopping andrestarting of the compressor is a predetermined constant time no matterhow long the operating cycle or what caused the compressor to stop.

FIG. 4

The embodiment of the invention shown in FIG. 4 is generally the same asshown in FIG. 3. However, this embodiment adds an extra period oftime tothe delay in restart ofthe compressor, if stopping is due to opening ofthe limit control switch. The extra delay added is the length of timethe limit control switch is open. In this embodiment of the invention,the instantaneous switch T-1 is closed by action of the timer but opensindependently of motion from the timer motor. The cam 30 is of theunifonn rise type having a sharp dropoff and operates a cam follower 31which is pivoted at 32. This cam follower operates a switch blade 33which is formed with a bracket 34 carrying a downwardly facing contact35. This contact cooperates with an upwardly facing contact on switchblade 36 having an end portion extending over the latch 37 which ispivoted at 38 and biased in a counterclockwise direction by a spring notshown. An insulating button 40 is carried by the switch blade 33 andserves to raise switch blade 36 along with blade 33 with the contactsseparated. In operation the cam 30 raises cam follower 31 which in turnraises blades 33 and 36 to their upper positions as shown. Here thecontacts are disengaged and the latch 37 has come into place under theend of switch blade 36. When the cam 30 rotates to the point where thecam follower engages the dropoff portion of the cam, the cam followermoves downwardly with snap action. Switch blade 36 is held by latch 37while switch blade 33 drops with the cam follower 31 causing thecontacts to engage. On continued downward movement of the follower 31,its end 42 engages the camming surface 43 on latch 37 causing this latchto be cammed clockwise in releasing direction. This releases latch 37from the switch blade 36 allowing this blade to drop, reengaging theinsulating button on switch blade 33. Thus the contacts disengage. Withthis arrangement, the timer motor causes the contacts to engage at apredetermined time. However, the contacts are caused to disengage in adefinite period of time determined by the time required for cam follower42 to disengage the latch 37.

In operation, assuming the limit control switch 16b is closed and thethermostat 15b calls for cooling, a starting circuit for the timer motoris established through these switches, lead 45, switch T-4, lead 46,timer motor lb and contactor coil 13b to line wire 18b. The timer motoris thus energized in series with the contactor coil 13b. The switchoperating chart is the same as shown in FIG. 5. Thus in about 10 secondsswitch T-4 opens and T-S closes which establishes a new circuit for thetimer motor through lead 47 which shunts out thermostat 15b. The circuitfor the timer motor in this case however, is through the limit controlswitch 16b. In approximately 15 seconds, the switch T-6 closesenergizing the blower motor. In approximately 20 seconds switch T-1closes which energizes the contactor coil 13b through leads 48, 49 and50. The contactor now pulls in, closing switches C-l, C-2 and 03. SwitchC-l is a holding switch for the contactor coil 13b maintaining the coilenergized in series with the limit control switch 16b and the thermostatswitch 15b. Contacts C-2 and C-3 on closing energize the compressor 14b.Switch T4 in closing creates a shunt circuit for the timer motor thusstopping the motor. This shunt circuit is maintained by closure of thecontactor holding contact C-l. Even though the timer motor lb stopped onclosure of switch T-l, this switch reopened by its own mechanism so thata complete revolution of the timer mechanism cam assembly must be madebefore the compressor can be restarted.

If the compressor operating cycle is terminated normally by thethermostat switch 15b, it will break the circuit for the contactor coilcausing the contactor to drop out, opening contacts C-1, C-2 and C-3.This stops the compressor and also breaks the shunt circuit for thetimer motor 1b. This motor will now start immediately and drive thetiming means back to the standby position, this action occurring duringthe off period of the compressor.

If the compressor is stopped by opening of the limit control switch 16b,it will drop out the contactor and stop the compressor. Opening of theholding contacts C-1 will break the shunt circuit for the timer motor.However, the timer motor will not operate at this time as its circuit isbroken at the switch 16b. The period of time the switch 16b is open isadded to the delay time provided by the timing mechanism before thecompressor can be restarted. In addition, the timing mechanism remainsstationary with the blower motor switch T-6 still closed which ensuresoperation of the blower motor during the entire time that the limitcontrol switch is open.

This helps alleviate the condition causing the limit control switch toopen.

FIGS. 6 and 7 In this embodiment of the invention, the timing mechanismprovides a fixed minimum delay time between stopping of the compressorand restart which is sufficient to provide for pressure equalization inthe system. This equalization delay time is run during the normal offtime of the compressor. This embodiment of the invention also providesan additional delay time in the event of a short cycle. This additionaldelay time is provided by operating the timer motor for a period of timeafter the compressor starts. In addition, this embodiment of theinvention provides for adding an indeterminate period of time to thedelay if the compressor is stopped by the limit control. This isaccomplished by preventing the timer from operating when the limitcontrol switch is open. In addition, this embodiment of the inventionprovides for control of the blower motor and for maintaining the blowermotor in operation when the compressor is stopped by the limit control.

The timing mechanism includes timer motor 1c operating cam operatedswitches T-l, ll, 22 and T-6. Switch T-l is of the same constructiondescribed in detail in connection with FIG. 1. Switch 11 is adouble-throw snap switch having a normally closed switch T-2 connectedto the contactor coil 13c along with switch T- l by lead 60. The commonterminal of switch 11 is connected to one side of the timer motor 16 bylead 61. Switch 11 also includes a normally open contact T-3 which isconnected to line wire 18c by lead 62.

Switch 22 is a double-throw snap switch having a normally closed contactT4 and a normally open contact T-S. The common terminal of this switchis connected by lead 63 to the other side of the timer motor 10. ContactT-S is connected between the limit control 16c and the thermostat 150 bylead 64 and contact T-4 is connected to the other side of the thermostat156 by lead 65.

In operation, assuming that the limit control switch 160 is closed, thethermostat 15c on call for cooling will establish a starting circuit forthe timer motor 1c from line wire 170 as follows: switch 16c, switch15c, lead 65, switch T-4, lead 63, timer motor 1c, lead 61, switch T-2,lead 60 and contactor coil 130 to line wire 18c. Thus on call forcooling, the thermostat establishes an initial starting circuit for thetimer motor in series with the contactor coil 130. As shown in FIG. 7,shortly after the timing means is started from the standby position,switch T-2 opens and switch T-3 closes. Also, switch T-4 opens andswitch T-5 closes. After these switches have operated as described, anew circuit for the timer motor is established which is independent ofthe thermostat 15c and also independent of the contactor coil 130. Thiscircuit is as follows: line wire 17c, limit switch 16c, lead 64, contactT-5, lead 63, timer motor lc, lead 61, switch T-3 and lead 62 to linewire 18c. Approximately 15 seconds from start, the switch T-6 closes,energizing the blower motor. In about 20 seconds from start, the timerswitch T-l closes energizing the contactor coil 13c. This closes thecontactor holding switch C-1 and also contactor switches C-2 and C-3energizing the compressor motor.

The timer motor continues operating for approximately 2 minutesindicated as Short Cycle Adder in the chart FIG. 7. At this time, switchT-3 opens and switch T-2 closes. This places the timer motor 10 inseries with the contactor coil 13c which is now energized by closure ofthe contactor holding switch CI. The timing motor at this time is nowshunted by holding switch C-1 and therefore stops at this point.

The system will remain in this condition in which the compressor motorand blower motor are in operation and the timer motor is stationaryuntil the thermostat l5c is satisfied or until the high-low pressure 16copens circuit. Assuming a normal cycle in which the thermostat becomessatisfied, it opens the circuit through holding switch 01 to contactorcoil 13: and deenergizes this coil causing contactor switches G1,

C-2 and O3 to open. This stops the compressor. It also breaks the shuntcircuit around the timer motor and allows this motor to run in serieswith the contactor coil 130. The energizing circuit for the contactorcoil is now open and it cannot be reclosed until the timer means runsback to the standby position and starts a new cycle. As shown in thechart FIG. 7, the timer after stopping the compressor, must run throughthe 4 minute 40 second equalization period plus the 20 second initialdelay period before the compressor can restart. Thus a minimum timing of5 minutes is interposed between the time the compressor stops and can berestarted.

In the event the system short cycles and compressor operation isterminated by the limit control 160, the timer must operate anadditional period before the compressor can be restarted. Thisadditional period added to the regular equalization period amounts tothe unused portion of the 2 minute Short Cycle Adder. Thus, if thecompressor stops 15 seconds after it starts, an additional 1 minute 45seconds is added to the normal delay time.

In addition to the additional delay imposed by the timing mechanism, thehigh-low pressure control 16c imposes another delay due to the fact thatit is in circuit with the timer motor 10. As long as the switch is open,the timer motor cannot be energized and thus this indeterminate periodof time is added to the balance of the Short Cycle Adder.

The embodiment of the invention disclosed in FIGS. 6 AND 7 thereforeprovides a normal equalization delay time between stopping and startingof the compressor, and a substantially longer period of time in case ofa short cycle. In addition, this embodiment of the invention alsomaintains the blower in operation for a substantial period of time afterreclosure of the limit control switch, thereby helping alleviate thecondition causing the short cycle.

From the foregoing description it will be apparent that the presentinvention provides a complete time control system for controlling arefrigeration compressor and blower motor and also for interposingdelays protecting the compressor from starting under load and fromburnouts caused by short cycling. It will also be apparent that theseresults are obtained by a reasonably simple timing mechanism and withoutrelays or complicated circuitry. While preferred forms of the inventionhave been shown and described, it is obvious that many modifications maybe made without departing from the spirit and scope of the invention.

lclaim:

I. In a control system for a refrigeration system having a compressormotor, a contactor for controlling said motor, said contactor having aswitch controlling the motor and a coil, a condition responsive means,timing means having an electric timing motor for driving the same, afirst timer-operated switching means connected in circuit with thecontactor coil for energizing the same to start the compressor motor, asecond timer-operated switching means connected to the timing motor,circuit means including the condition responsive means and the secondtimer switching means for causing operation of the timing motor uponcall for a condition change by the condition responsive means, thetiming means being arranged to actuate the first switching means aperiod of time thereafter, the circuit means being arranged to place thetiming motor in series with the contactor coil and to complete a shuntcircuit for the timing motor for stopping the same at a predeterminedposition when the contactor coil is energized, and to break the shuntcircuit when the contactor coil is deenergized, providing the timingmotor a starting circuit in series with the contactor coil.

2. The combination as defined in claim 1 in which the conditionresponsive means and the first timer switching means in series form partof the shunt circuit for the timing motor, and in which the second timerswitching means provides a circuit to immediately restart the timingmotor when the shunt circuit is broken, the first switching means beingarranged to open a short period of time thereafter to delay restart ofthe compressor.

3. The combination as defined in claim 1 in which the shunt circuitincludes a holding switch operated by the contactor, said holding switchbeing opened when the contactor coil is deenergized.

4. The combination as set forth in claim 1 in which the first timerswitching means includes means independent of the timer motor forreopening said switching means instantly without movement of the timingmotor, and in which the shunt circuit is maintained by a holding switchoperated by the contactor.

5 The combination as defined in claim 1 in which the second timerswitching means is arranged to place the timing motor either in serieswith or in parallel with the contactor coil.

6. The combination as set forth in claim 1 in which the second timerswitching means establishes a shunt circuit for the condition responsivemeans so that the timing motor is restarted immediately when thecontactor coil is deenergized, said second switching means returning thetiming motor to control by the condition responsive means at apredetermined position of the timing means.

7. The combination set forth in claim 6 in which a third timer-operatedswitching means maintains the timing motor in operation for a period oftime after the contactor is energized, and then places the timing motorin series with the contactor coil for stopping the timing motor untilthe contactor coil is deenergized.

8. The combination set forth in claim 6 in which refrigeration systemincludes a blower and in which a third switching means operated by thetiming means controls the blower in a manner to start the blower atleast by the time the compressor is started and to maintain the blowerin operation for a period of time after the compressor is stopped.

9. The combination as set forth in claim 6 in which a safety controllerresponsive to an unfavorable condition associated with the refrigerationsystem is connected to deenergize both the contactor coil and timingmotor, whereby the compressor is stopped in response to such unfavorablecondition and the timer is prevented from timing as long as theunfavorable condition exists.

10. The combination as set forth in claim 8 in which a safety controllerresponsive to an unfavorable condition associated with the refrigerationsystem is connected to deenergize both the contactor coil and the timingmotor as long as the unfavorable condition prevails, thus maintainingthe blower in operation.

11. In a control system for a refrigeration system having a compressormotor, a contactor for controlling said motor, said contactor having aswitch controlling the motor and a coil, means for controlling saidcontactor coil including a condition responsive means and a timing meanshaving an electric timing motor, the condition responsive means beingarranged to cause starting of the compressor motor on call for conditionchange, and to stop the compressor motor on call for condition change,and to stop the compressor motor when satisfied, and the timing meansbeing arranged to provide a delay between stopping and restarting of thecompressor motor, means for stopping the timing means at a firstpredetermined position in its cycle after the compressor motor isstarted, said last-named means including timer-operated switching meansand circuit means placing the electric timer motor in series with thecontactor coil and providing a shunt circuit for the timer motor whenthe contactor coil is deenergized, means independent of the conditionresponsive means for completing the energizing circuit to the timermotor when the contactor coil is deenergized causing the timer motor tostart driving the timing means from said first predetermined position,and means for stopping said timing means at a second predeterminedposition.

12. In a control system for a refrigeration system having a compressormotor, a contactor for controlling said motor, said contactor having aswitch controlling the motor and a coil, means for controlling saidcontactor coil including a condition responsive means and a timing meanshaving an electric timing motor, the condition responsive means beingarranged to cause starting of the compressor motor on call for conditionchange, and to stop the compressor motor when satisfied, and the timingmeans being arranged to provide a delay between stopping and restartingof the compressor motor, means for causing operation of the timing motorand movement of the timing means for a predetermined time after thecompressor motor is started for providing a variable delay betweenstopping and restarting of the compressor motor depending on the lengthof time the compressor motor operates, said lastnamed means includingcircuit means for the timing motor including switching means operated bythe timing means at said predetermined time providing a power circuitfor the timing motor in series with the contactor coil whereby thetiming motor is shunted at said predetermined time if the contactor coilis energized, and the contactor coil provides a portion of an energizingcircuit for the timing motor when the contactor coil is deenergized.

13. In a control system for a refrigeration system having a compressormotor, a contactor for controlling said motor, said contactor having aswitch controlling the motor and a coil, means for controlling saidcontactor coil including a condition responsive means and a timing meanshaving an electric timing motor, the condition responsive means beingarranged to cause starting of the compressor motor on call for conditionchange, and to stop the compressor motor when satisfied, and the timingmeans being arranged to provide a delay between stopping and restartingof the compressor motor, means for causing operation of the timing motorand movement of the timing means for a predetermined time after thecompressor is started for providing a variable delay between stoppingand restarting of the compressor depending on the length of time thecompressor operates, said last-named means including circuit means forthe timing motor including switching means for operated by the timingmeans at said predetermined time providing a power circuit for thetiming motor in series with the contactor coil whereby the timing motoris shunted at said predetermined time if the contactor coil isenergized, and the contactor coil provides a portion of an energizingcircuit for the timing motor when the contactor coil is deenergized,means independent of the condition responsive means for completing theenergizing circuit to the timing motor when the contactor coil isdeenergized causing the timing motor to start driving the timing meansfrom the position it stopped when shunted, and means for stopping saidtiming means at a predetermined position.

14. [n a control system for a refrigeration system having a compressormotor, a contactor for controlling said motor, said contactor having aswitch controlling the motor and a coil, a condition responsive means,timing means having an electric timing motor for driving the same, afirst timer-operated switching means connected in circuit with thecondition responsive means and the coil, said first timer switchingmeans being arranged to close at a predetermined position of the timingmeans for energizing the contactor coil under the control of thecondition responsive means, said first switching means also beingarranged to be reopened by the timing means when it travels a shortdistance beyond said predetermined point, a second timer-operatedswitching means, one side of the timer motor being connected to saidsecond switching means and the other side of the timer motor beingconnected to the contactor coil in a manner causing the contactor coilto form part of a power circuit for the timer motor, the secondtimeroperated switching means being arranged to connect said one side ofthe timer motor to the condition responsive means when in a firstposition and to provide a circuit for the timer motor shunting thecondition responsive means when in a second position, said timing meansbeing arranged to actuate said second switching means from its firstposition to its second position before closure of the first switchingmeans, and to return the second switching means to its first position aperiod of time after opening of the first switching means.

1. In a control system for a refrigeration system having a compressormotor, a contactor for controlling said motor, said contactor having aswitch controlling the motor and a coil, a condition responsive means,timing means having an electric timing motor for driving the same, afirst timer-operated switching means connected in circuit with thecontactor coil for energizing the same to start the compressor motor, asecond timer-operated switching means connected to the timing motor,circuit means including the condition responsive means and the secondtimer switching means for causing operation of the timing motor uponcall for a condition change by the condition responsive means, thetiming means being arranged to actuate the first switching means aperiod of time thereafter, the circuit means being arranged to place thetiming motor in series with the contactor coil and to complete a shuntcircuit for the timing motor for stopping the same at a predeterminedposition when the contactor coil is energized, and to break the shuntcircuit when the contactor coil is deenergized, providing the timingmotor a starting circuit in series with the contactor coil.
 2. Thecombination as defined in claim 1 in which the condition responsivemeans and the first timer switching means in series form part of theshunt circuit for the timing motor, and in which the second timerswitching means provides a circuit to immediately restart the timingmotor when the shunt circuit is broken, the first switching means beingarranged to open a short period of time thereafter to delay restart ofthe compressor.
 3. The combination as defined in claim 1 in which theshunt circuit includes a holding switch operated by the contactor, saidholding switch being opened when the contactor coil is deenergized. 4.The combination as set forth in claim 1 in which the first timerswitching means includes means independent of the timer motor forreopening said switching means instantly without movement of the timingmotor, and in which the shunt circuit is maintained by a holding switchoperated by the contactor.
 5. The combination as defined in claim 1 inwhich the second timer switching means is arranged to place the timingmotor either in series with or in parallel with the contactor coil. 6.The combination as set forth in claim 1 in which the second timerswitching means establishes a shunt circuit for the condition responsivemeans so that the timing motor is restarted immediately when thecontactor coil is deenergized, said second switching means returning thetiming motor to control by the condition responsive means at apredetermined position of the timing means.
 7. The combination set forthin claim 6 in which a third timer-operated switching means maintains thetiming motor in operation for a period of time after the contactor isenergized, and then places the timing motor in series with the contactorcoil for stopping the timing motor until the contactor coil isdeenergized.
 8. The combination set forth in claim 6 in whichrefrigeration system includes a blower and in which a third switchingmeans operated by the timing means controls the blower in a manner tostart the blower at least by the time the compressor is started and tomaintain the blower in operation for a period of time after thecompressor is stopped.
 9. The combination as set forth in claim 6 inwhich a safety controller responsive to an unfavorable conditionassociated with the refrigeration system is connected to deenergize boththe contactor coil and timing motor, whereby the compressor is stoppedin response to such unfavorable condition and the timer is preventedfrom timing as long as the unfavorable condition exists.
 10. Thecombination as set forth in claim 8 in which a safety controllerresponsive to an unfavorable condition associated with the refrigerationsystem is connected to deenergize both the contactor coil and the timingmotor as long as the unfavorable condition prevails, thus maintainingthe blower in operation.
 11. In a control system for a refrigerationsystem having a compressor motor, a contactor for controlling saidmotor, said contactor having a switch controlling the motor and a coil,means for controlling said contactor coil including a conditionresponsive means and a timing means having an electric timing motor, thecondition responsive means being arranged to cause starting of thecompressor motor on call for condition change, and to stop thecompressor motor on call for condition change, and to stop thecompressor motor when satisfied, and the timing means being arranged toprovide a delay between stopping and restarting of the compressor motor,means for stopping the timing means at a first predetermined position inits cycle after the compressor motor is started, said last-named meansincluding timer-operated switching means and circuit means placing theelectric timer motor in series with the contactor coil and providing ashunt circuit for the timer motor when the contactor coil isdeenergized, means independent of the condition responsive means forcompleting the energizing circuit to the timer motor when the contactorcoil is deenergized causing the timer motor to start driving the timingmeans from said first predetermined position, and means for stoppingsaid timing means at a second predetermined position.
 12. In a controlsystem for a refrigeration system having a compressor motor, a contactorfor controlling said motor, said contactor having a switch controllingthe motor and a coil, means for controlling said contactor coilincluding a condition responsive means and a timing means having anelectric timing motor, the condition responsive means being arranged tocause starting of the compressor motor on call for condition change, andto stop the compressor motor when satisfied, and the timing means beingarranged to provide a delay between stopping and restarting of thecompressor motor, means for causing operation of the timing motor andmovement of the timing means for a predetermined time after thecompressor motor is started for providing a variable delay betweenstopping and restarting of the compressor motor depending on the lengthof time the compressor motor operates, said last-named means includingcircuit means for the timing motor including switching means operated bythe timing means at said predetermined time providing a power circuitfor the timing motor in series with the contactor coil whereby thetiming motor is shunted at said predetermined time if the contactor coilis energized, and the contactor coil provides a portion of an energizingcircuit for the timing motor when the contactor coil is deenergized. 13.In a control system for a refrigeration system having a compressormotor, a contactor for controlling said motor, said contactor having aswiTch controlling the motor and a coil, means for controlling saidcontactor coil including a condition responsive means and a timing meanshaving an electric timing motor, the condition responsive means beingarranged to cause starting of the compressor motor on call for conditionchange, and to stop the compressor motor when satisfied, and the timingmeans being arranged to provide a delay between stopping and restartingof the compressor motor, means for causing operation of the timing motorand movement of the timing means for a predetermined time after thecompressor is started for providing a variable delay between stoppingand restarting of the compressor depending on the length of time thecompressor operates, said last-named means including circuit means forthe timing motor including switching means for operated by the timingmeans at said predetermined time providing a power circuit for thetiming motor in series with the contactor coil whereby the timing motoris shunted at said predetermined time if the contactor coil isenergized, and the contactor coil provides a portion of an energizingcircuit for the timing motor when the contactor coil is deenergized,means independent of the condition responsive means for completing theenergizing circuit to the timing motor when the contactor coil isdeenergized causing the timing motor to start driving the timing meansfrom the position it stopped when shunted, and means for stopping saidtiming means at a predetermined position.
 14. In a control system for arefrigeration system having a compressor motor, a contactor forcontrolling said motor, said contactor having a switch controlling themotor and a coil, a condition responsive means, timing means having anelectric timing motor for driving the same, a first timer-operatedswitching means connected in circuit with the condition responsive meansand the coil, said first timer switching means being arranged to closeat a predetermined position of the timing means for energizing thecontactor coil under the control of the condition responsive means, saidfirst switching means also being arranged to be reopened by the timingmeans when it travels a short distance beyond said predetermined point,a second timer-operated switching means, one side of the timer motorbeing connected to said second switching means and the other side of thetimer motor being connected to the contactor coil in a manner causingthe contactor coil to form part of a power circuit for the timer motor,the second timer-operated switching means being arranged to connect saidone side of the timer motor to the condition responsive means when in afirst position and to provide a circuit for the timer motor shunting thecondition responsive means when in a second position, said timing meansbeing arranged to actuate said second switching means from its firstposition to its second position before closure of the first switchingmeans, and to return the second switching means to its first position aperiod of time after opening of the first switching means.